Color dye transfer thermal printers use a dye donor in the form of a sheet or a continuous web advanced from a supply roll. Typically, three continuous webs are employed (corresponding to the three fundamental color dyes used) individually or in tandem, to generate the appropriate color and its hue and contrast attributes. The dye donor passes between the dye receiver and a thermal printhead. The printhead consists of a linear array of thermal elements that are selectively energized resulting in an image transfer from the dye donor to the dye receiver.
A significant problem exists in this technology. The transfer mechanism is intended as a single use or a one time event. To print a black image (text or graphics), all three color dye webs are utilized. This results in only a small fraction of each dye being used. After printing, the dye donors cannot be easily reused and are therefore discarded.
The cost of having a single use dye donor web(s) is high because a large surface area of dye donor is required, but only a fraction of the area is utilized to generate the image. Additionally, recycling the used webs can also impact on the cost of such a system.
It has been proposed that a reusable closed looped web (belt) replace the single-use web. The donor dye(s) can then be sublimed in the correct proportions in just the image area. The dye is then transferred to the dye receiver using a thermal print head.
However, even this closed looped system can be problematic. The web material is usually a plastic polymer, such as polyester. The wear and distortions on this belt may limit its life time dramatically. Additionally, continuous control of regeneration of distinguishable color dye transfer to the belt will similarly limit its use and lifetime.
There is thus a need for an improved closed looped dye donor element that can be utilized in thermal printing to provide cost effective continuous thermal dye transfer mechanism with extended life.